Means for ventilating tunnels.



UNITED STATES nTnNT FFICE.

VIRGINIA.

MEANS FOR VENTILATING TUNNELS.

SPECIFICATIGN forming part of Letters Patent No. 689,039, dated December 17, 1901. Application filed July 15, 1901. Serial No. 68,375. (No model.)

To all whom it may concern.-

Be it known that we, CHARLES S. CHURCH- ILL and CHARLES C. WENTWORTH, citizens of the United States,residin g at Roanoke, county of Roanoke, State of Virginia, have invented certain new and useful Improvements in Means for Ventilating Tunnels, of which the following is a specification.

Our invention relates to means for ventilating tunnels, and more particularly to an improvement upon the construction disclosed and claimed in our Patent No. 671,264, granted April 2, 1901.

The object of our invention is to provide a construction of discharge-nozzle through which the air-blast is blown into the tunnel in the manner described in our prior patent,

above mentioned, which will prevent the possibility of formation of eddies in the current at certain points adjacent to said dischargenozzle, such eddies tending to some extent to create a slight counter-current, and thus vary the velocity or flow of the current of air through an opening which extends around the arch and down the sides while there is a current on either side to balance the current.

on the other side of the tunnel there is no on rrent at the bottom to balance that which is delivered at the top or apex of the air-blast opening. While these eddies do not materially affect the efficiency of our prior patented construction so far as the function of ventilation of the tunnel is concerned, they are yet objectionable under some conditionsin so far as they tend to create a counter current, though to a slight extent, at points near the bottom of the tunnel, and therefore we regard means for avoiding or preventing them to be in the direction of greater perfection,

and for this reason our present invention is an improvement upon our prior construction.

WVith the above object in view our invention consistsin the novel construction hereinafter described and claimed with reference to the accompanying drawings, in which- Figure 1 is a central longitudinal section of a portion of the tunnel, showing our invention applied to one end. Fig. 2 is a vertical section on the line 2 2, Fig. 1. Fig. 3 is a longitudinal section of a modified form.

Referring to the drawings, in which the same reference characters refer to the same or corresponding parts in all the views, and in which a ventilating plant operating upon the same principle as that disclosed in our prior patent is shown, the numeral 1 indicates a section of a tunnel, while the numeral 2 indicates the inner Wall thereof, which tunnel is of the usual cross-section. Within the walls of the tunnel is formed an air-chamber 3, extending around the sides and top of the tunnel, the outer wall 4 of said chamber being preferably inclined, while the inner wall 5 is parallel to the axis of the tunnel and is a prolongation of the inner wall 2 of the tunnel, thus forming a tapered chamber. The discharge-opening '7 for the air terminates the chamber 3 and is formed as in the prior patent. This discharge-opening, it will be observed, is formed by the inner wall of the tunnel and the extremity 6 of the inner Wall of the chamber 3, said extremity being preferably tapered to reduce to a minimum the tendency to the formation of eddies in the current of air discharged through the nozzle thus formed.

The outer end of the air-chamber is closed by an end wall 8 of the tunnel, through which end wall is an opening to which is attached a discharge-pipe 9, extending from a blower 10 and driven by any suitable motor, such as an engine 11.

In our prior patent the tapered edge 6, forming the inner wall of the contracted airoutlet, extends vertically, as indicated by dotted lines 3 3, Fig. 1, so that the air-blast is discharged simultaneously at all points around the top and sides of the tunnel at the same velocity and in the same volume, and as a consequence there is a tendency for the blast to form an eddy, as indicated by arrow A in Fig. 1, because of the fact that there is no current discharged at the bottom to counterbalance the current discharged at the top. In order to overcome this objection, we have found that by forming the end of the wall 6 on an incline downwardly in a direction contrary to the direction of air-blast as it leaves the nozzle, as shown in Fig. 1, the desired result is attained. This construction permits the air to leave the nozzle at points gradually approaching nearer the closed end of the chamber as the nozzle approaches the bottom or that side of the tunnel Where there is no discharge. The effect of this construction is to bring the center of gravity of the air-blast more nearly coincident with the center of gravity of the tunnel-section, so that there is no ovcrbalancing of one portion of the blast with respect to the other, and thus the eddies hereinbefore mentioned are avoided.

It should be noted that the relation between the inner wall of the tunnel and the inner wall of the chamber 3 is the same as in our prior construction; but the area of the nozzleopening gradually increases toward the bottom, as shown in Fig. 2.

Instead of inclining the entire edge of the discharge end of the chamber 3 from top to bottom we may in many instances form this edge as shown in Fig.3, where the inclined edge of the discharge end of the chamber is indicated by 6", which lies in an inclined plane beginning at a point slightly below the crown of the tunnel on each side, such discharge end being then composed of a portion 13, lying in a vertical plane or in a plane at right angles to the axis of the tunnel, and an inclined portion 6, which lies in a plane inclined with respect to the other portion.

Other modified forms of the tapered discharge-opening may be used without departing from the spirit of our invention as hereinafter claimed, such forms being dependent upon the cross-section of the tunnel, the lineal extent of the nozzle with respect to the said cross-section, and the consequent relation between the centers of gravity of the tunnel-section and the air-blast, the essential requisite being that the centers of gravity of the tunnel-section and the air-blast shall be made to approach as nearly to-coincidence as it is possible to attain. The position of the nozzle opposite that side of the tunnel in which there is no nozzle-section extends,therefore, in advance of the lower portions with respect to the direction in which the air flows.

With the discharge-nozzle constructed as hereinbefore described it will be observed that the air-blast is discharged into the tunnel from the chamber 3 in the manner described in our prior patent, so that the said blast will enter the tunnel in a direction substantially parallel to the axis of the tunnel and adjacent to the walls of said tunnel.

'- This mode of operation is the same as in our prior patented construction, the effect of the air, blown into the tapered chamber 3 being to cause the air to issue through the nozzle 7 at an accelerated velocity adjacent to the walls of thetunnel in lines substantially parallel to the axis of thetunnel, therebyinducing a current through the tunnel, and thus clearing the same of foul air and deleterious gases, which are replaced by fresh air following said induced current.

What We claim, and desire to secure by Letters Patent, is-

1. In a ventilating system for tunnels, the combination with the tunnel, of a chamber formed in the wall of said tunnel, said chamber terminating in an opening adapted to discharge a blast of air into the tunnel and extending partly around the tunnel-section, the edge of one portion of said opening extending in a direction opposite to the course of the air-blast to a point in rear of the other portions thereof, with respect to the direction of the discharge of air therefrom, and means for blowing a blast of air into the chamber, substantially as described.

2. In a ventilating system for tunnels, the combination with the tunnel, of an air-chamber formed in the wall of said tunnel, theinner Wall of which chamber is substantiallyin line with the inner wall of the tunnel and forming with the tunnel wall an opening adapted to discharge air therefrom, in a direction substantially parallel to the axis of the tunnel, and adjacent to the walls thereof, theedge of the air-chamber forming the discharge end of said chamber being inclined in a direction contrary to the course of the air-blast, and means for blowing a blast of air into said chamber, whereby the blast of air issuing from the chamber into the tunnel will create a current through the tunnel and eddies in the current will be prevented, substantially as described.

3. In a ventilating system for tunnels, the combination with the tunnel, of an air-chamber formed in the wall of said tunnel, the inner wall of which chamber is substantiallyin line with the inner wall of the tunnel, and forming with the tunnel-wall an opening adapted to discharge air therefrom in a direction substantially parallel to the axis of the tunnel and adjacent to the walls thereof, the edge of the inner wall of the chamber forming the discharge end of said chamber terminating in a portion lying in a plane at right angles to the axis of the tunnel near the top portion, and extending in a plane inclined in the opposite direction to the course of the air-blast, substantially as described.

4. In a ventilating system for tunnels, the

combination with the tunnel, of an air-chamber forming the walls thereof, said chamber terminating in a nozzle adapted to discharge air into the tunnel adjacent to the walls thereof, and substantially parallel to the axis of the tunnel, said nozzle having its discl1arging edge inclined in the opposite direction to names to this specification in the presence of the course of the air-blast so that the center two subscribing witnesses.

i of gravity of the air-blast discharged therefrom is substantially coincident with the cenr 5 terof gravity of the tunnc1-section,and means for blowing air into said air-chamber, sub- Witnesses: stantiaily as described. JOHN J. QUINN,

In testimony whereof We have signed our E. J. ROWAN. 

